Currently, many computer systems are built to support user sessions around the clock. Such systems will often run various programs and applications that require periodic patches or upgrades. Because most programs and applications have various version upgrades and patches, a system administrator will usually upgrade the system when a new version or patch becomes available in order to assure that the system runs smoothly and efficiently.
A typical system upgrade requires that the system be brought down or taken off line for a considerable amount of time. Then, the system is upgraded and tested, and after a successful test it is brought back online. For systems that are live, this downtime may be extensive and therefore cause user frustration and disappointment.
Additionally, an upgrade itself may turn out to be unsuccessful. And, a failed upgrade may even prolong the system's downtime. As a result of an unsuccessful upgrade, the old version of a system would need to be restored and data would need to be rescued and reconciled. Sometimes, data may be inadequately rescued or some of it may not be rescued at all, and the system will thus run on obsolete data. Using obsolete data may lead to further system errors and end-user frustration and disappointment.
The present methods for upgrading a system are, therefore, inadequate. It would be desirable to lessen the downtime associated with upgrading a system. It would also be desirable to bring back and restore a previous version of a system or program without unnecessary downtime. It is further desirable to sufficiently test the upgraded version of a system before resuming critical applications, thereby again extending the downtime of the system.
Therefore, there exists a need for an improved method and system for upgrading live systems.